Packing of electrodes in an electric arc furnace

ABSTRACT

An electrode sealing packing of an electric arc furnace is characterized in that it comprises at least two rows of movable packing segments radially pressed against the electrode by a tightening device and disposed one above another on a watercooled box mounted on a furnace roof in the zone of an electrode opening; said tightening device is made in the form of a weight ring with tightening rods whose one end is articulated with the weight ring and the other with the packing segments ensuring the clamping of the segments to the electrode on account of the weight of the ring with the lateral edges of a packing segment of the lower row being parallel to the axis of motion of the segment and the spacings between the packing segments of the lower row accommodating plates similar in shape to that of the spacings, the plates being rigidly connected with each other forming a ring loosely resting on the water-cooled box.

United States Patent Salmin et al.

[54] PACKING OF ELECTRODES IN AN ELECTRIC ARC FURNACE [72] Inventors:Valery Vasilievich Salmin, ulitsa Zorge, 95, kv. 69; Ivan PetrovichNechaev, ulitsa Sibiryakov-Gvardeitsev, 22, kv. 35, both of Novosibirsk,USSR.

22 Filed: July 14, 1971 21 Appl.No.: 162,423

[52] US. Cl. ..13/17 [51] Int. Cl. ..I-l05b 7/10 [58] Fieldof Search..113/l4, l5, l6, 17

[56] References Cited UNITED STATES PATENTS 1,732,431 lO/1929 Bruggmann..13/l7 2,979,550 4/1961 Sherman, Sr. ..l3/17 1 Aug. 8, 1972 PrimaryExaminer-Bernard A. Gilheany Assistant Examiner-R. N. Envall, Jr.

[5 7] ABSTRACT ments to the electrode on account of the weight of thering with the lateral edges of a packing segment of the lower row beingparallel to the axis of motion of the segment and the spacings betweenthe packing seg ments of the lower row accommodating plates similar inshape to that of the spacings, the plates being rigidly connected witheach other forming a ring loosely resting on the water-cooled box.

2 Claims, 2 Drawing Figures PACKING OF ELECTRODES IN AN ELECTRIC ARCFURNACE The present invention relates to steel-melting electric arcfurnaces, where the problem of efiicient packing of a gap between anelectrode and a furnace roof is most acute due to specific featurespeculiar to the technology of production of electric steel andconstructional characteristics of metallurgical units in question; andmore particularly the present invention is directed to packing ofelectrodes in electric arc furnaces.

Known at present are various kinds of electrode packings of diversifieddesign, which may be subdivided into three groups.

The first one includes devices in which packing is provided by somemechanical means.

The second group comprises devices in which packing is effected byblowing gas /air or nitrogen/ into a gap between the electrode and theroof.

The third group comprises composite devices which represent acombination of the first two groups.

Known in prior art is an electrode packing of the mechanical type, madein the form of a ring of either ceramic or metallic segmentsencompassing the electrode above a watercooled box, with each segmentarticulated with a weight suspended in such a manner that a moment ofsaid weight produced ensures a constant force pressing the segmentsagainst the electrode.

However the above electrode packing is too cumbersome and does notprovide dependable and troublefree operation.

Also known is an electrode packing in the form of a collar made up ofseveral segments articulated with each other by means of pins. Theextreme segments in this arrangement are fitted with arms from which aload chain is suspended with the weight component of the chain producinga force pressing the segments against the electrode.

The aforesaid arrangement however does not ensure an efficient packingof electrodes of variable cross-section.

Known also is an electrode packing which consists of I developed for anelectric arc furnace a tightening a set of plates assembled in packs torock about a pivot.

The plate packs disposed along the electrode perimeter are fastened on awater-cooled box.

The pivot holes in the plates are displaced toward the electroderelative to the plate center of gravity, producing a moment of the plateweight which assures a constant force pressing the plates against theelectrode.

In operation the spacings between adjoining plates are liable to collectdust and are exposed to schorching, by which virtue the plates loosetheir mobility and the device becomes non-serviceable.

Known in the prior art is an electrode packing made up of individualcooled sections disposed in two rows around the electrode.

The exterior of the sections in the inner row facing the electrodeconform to the electrode shape.

The sections are loosely suspended from anns held by rollers at acertain angle to the horizontal so that their weight component creates aforce holding them tight to the electrode. The rollers are secured tothe supports of a ring-shaped sheet mounted on a roof lining. Jointsbetween individual sections are overlapped by a row of external sectionsarticulated with the latter by means of arms.

Spacings between the section collar and the ring shaped sheet areoverlapped by two rows of sheet sectors with the lower one being coupledwith mobile sections and the upper with the stationary ring-shapedsheet.

The above packing devices have too sophisticated a construction andinadequate efiiciency.

Apart from the varieties of electrode packings stated above in which theproblem of providing a packing in a gap between an electrode and a roofis solved by mechanical means, known also is an electrode packing, inwhich the packing action is provided by a gas /air or nitrogen/ into thegap between the electrode and the furnace roof.

However such electrode packings are not dependable enough in service anddo not provide an efiicient sealing of the electrodes. Also inherent inmechanical packings is either low efficiency or an intricateconstruction and inadequate reliability in operation.

Dynamic gas packings tend to cause an intense oxidation of theelectrodes and either hamper the production of a reducing atmosphere inthe furnace in case air is blown/ or are extremely expensive lwherenitrogen is employed for blowing in/. Composite packings suffer from thedrawbacks peculiar to both types.

Owing to the foregoing disadvantages none of the conventional electrodepackings has received wide application particularly due to shortcomingsinherent in each type.

It is an object of the present invention to eliminate the above saiddrawbacks.

The present invention is in essence aimed at developing a packing forelectrodes of an electric arc furnace which would be reliable inoperation ensuring an efficient sealing of a gap between each electrodeand the furnace roof at the same time featuring adequate overalldimensions, ease of maintenance and lack of sensitivity to thermalloads.

According to this invention, the specified object is achieved by thefact that in an electrode packing device is made in the form of a weightring with tightening rods articulated with one end with a weight ringwhile their other end is hinged to mobile segments, by virtue of whichthe segments are clamped to the electrode due to the ring weight, withthe lateral edges of each segment in a lower row being parallel to anaxis of motion of the segment and with spacings between the adjoiningsegments accommodating plates similar in shape to that of the spacings.

It is expedient to connect the plates rigidly with each other to form aring resting freely on a water-cooled box and to hold the plates inplace with the aid of the segments in setting up and removing them fromthe cooled box.

In compliance with the present invention, the proposed electrode packingprovides for an efficient sealing of the gaps between the electrode andthe roof, reducing heat losses to a permissible value and improvingatmospheric conditions in a shop.

It is noteworthy that simple construction and small overall dimensionsof the proposed device result in high reliability and convenience inmaintenance along with thermal stability.

The electrode packing is best suited for electric arc steel-meltingfurnaces, and especially for such furnaces as are equipped with unitsfor the removal of furnace gases directly from the furnace workingchamber.

In addition it is also applicable in electrothennal apparatus withmobile electrodes passing through the roof, where tightening of the gapbetween the electrode and the furnace roof to an ideal level is notrequired.

Given below is a description of a design of the proposed device and itsoperation to be considered with due reference to the appended drawings,wherein:

FIG. 1 is a cross-sectional view of electrode packing, conforming to theinvention.

FIG. 2 shows a top view of FIG. 1 with a weight ring and an upper row ofsegments shown fragmentary.

With reference to the figures an electrode packing consists of awater-cooled box I mounted on a furnace roof in the zone of an electrodeopening, mobile segments 2 and 3 arranged in two rows an upper and aIowerone accordingly, clamped by a tightening device comprisingtightening rods 4 linked mechanically with each other and a weight ring5. Packing segments 2 and 3 of the upper and lower rows respectively arearticulated by means of tightening rods 4 with weight ring 5. This iseffected'with the aid of pins 6 passing through ears 7 of the weightring and ears 8 of packing segments 2 and 3. Bars 8 act as the guidesfor the packing segments 2 and 3.

Lateral edges of packing segments 3 of the lower row are parallel to theaxes of motion of segments 3, directed toward the center point ofelectrode 9. The spacings between the packing segments 3 of the lowerotht e a s between th ad' ini kin s t g and 3 the angle inclinati n gfroxfs 313 chosen as to ensure the clamping of packing segments 2 rowaccommodate plates 10 similar in shape to that of the spacings and equalin thickness to that of packing segments 3. Plates 10 are rigidlycoupled with each other by means of ring 11. An inner diameter of ring11 is slightly smaller than the outer diameter of the lower row ofpacking segments 3 to enable ring 11 to be raised with plates 10 bypacking segments dun'ng erection and removal.

The electrode packing functions as follows. Ringshaped water-cooled box1 protects a region of the lining of furnace roof l2 adjoining electrode9 and mechanical elements incorporated in the packing construction fromexcessive heat. For better sealing of the proposed device water-cooledbox 1 is mounted on refractory layer I3 applied to the lining of roof I2in the zone of electrode opening 14. With the proposed arrangementpacking segments 2 and 3 made of heat-resisting low-magnetic material(for example, of a heatproof alloy of an austenitic class or of anon-metallic refractory material of the type of a graphite-containingceramics) acts as the main packing element. For better overlapping ofthe gap between electrode 9 and watercooled box 1 mobile packingsegments 2 and 3 are arranged in two rows overlapping so that the gapsbetween packing segments 3 in the lower row overlap and 3 to electrode 9with a cone-shaped working end therefor. When a new electrode 9 with acylindrical end is inserted into the packing, segments 2 and 3 are movedapart by cars 8 provided on packing segments 2 and 3 and acting at oneand the same time as the lugs for fastening rods 4. The spacing betweenpacking segments 3 of the lower row needed to ensure their radialmovement in a horizontal plane are overlapped by plates 10. The lateraledges of packing segments 3 being parallel to their axes of respectivedisplacement plates 10 do not interfere with the movement of packingsegments 2 and 3 under the action of weight ring 5 with a minimum valueof the straight gaps between plates and segments 2 and 3. Being rigidlycoupled with each other by means of ring 11 plates 10 are freely restingon water-cooled box 1, through which the entire packing system isself-aligning with electrode 9.

In setting up and removing weight ring 5 with packing segments 2 and 3on cooled box 1, ring 11 together with plates 10 is held in place by thelower row of packing segments 3, being set up or taken off together withthe latter. 1

WHAT IS CLAIMED IS:

1. An electrode packing arrangement to seal an electrode where it entersan electric arc furnace, comprising: a water-cooled box, mounted on afurnace roof in the zone of an opening in the furnace through whichopening the electrode is introduced; at least two rows of packingsegments, arranged one above the other on said water-cooled box toconstitute lower and upper rows; a tightening device clamping saidpacking segments and radially biasing the segments into sealingengagement with the electrode, said tightening device made in the formof a weight-ring with tightening rods one end of each of the rods beingarticulated with the weight-ring and the other end of each of said rodsbeing articulated with the packing segments ensuring the pressing of thesegments against the electrode on account of the weight of theweight-ring, with lateral edges of one segment of the lower row beingparallel to the axis of motion of said one segment; plates disposed inspacings between adjacent packing segments of the lower row and similarin shape to that of the spacings.

2. An electrode packing for an electric arc furnace, as in Claim 1, inwhich said plates are rigidly coupled with each other forming a ringloosely resting on the water-cooled box and held in place by the packingsegments in their setting up and removal from the watercooled box.

1. An electrode packing arrangement to seal an electrode where it entersan electric arc furnace, comprising: a water-cooled box, mounted on afurnace roof in the zone of an opening in the furnace through whichopening the electrode is introduced; at least two rows of packingsegments, arranged one above the other on said water-cooled box toconstitute lower and upper rows; a tightening device clamping saidpacking segments and radially biasing the segments into sealingengagement with the electrode, said tightening device made in the formof a weight-ring with tightening rods one end of each of the rods beingarticulated with the weight-ring and the other end of each of said rodsbeing articulated with the packing segments ensuring the pressing of thesegments against the electrode on account of the weight of theweight-ring, with lateral edges of one segment of the lower row beingparallel to the axis of motion of said one segment; plates disposed inspacings between adjacent packing segments of the lower row and similarin shape to that of the spacings.
 2. An electrode packing for anelectric arc furnace, as in Claim 1, in which said plates are rigidlycoupled with each other forming a ring loosely resting on thewater-cooled box and held in place by the packing segments in theirsetting up and removal from the water-cooled box.